Vehicle manufacturers have realized that it may be desirable under some conditions to automatically start and stop an engine of a vehicle. Stopping the engine can reduce fuel consumption, especially when the vehicle is stopped for longer periods of time, in stop-and-go traffic for example. However, supplying the driver with a desired amount of wheel torque shortly after engine restart may be difficult because of torque management within a transmission. For example, if transmission clutches are in an open state during engine starting, a wheel torque response delay may be perceived by the driver. Further, the timing at which torque is transferred through the transmission may vary from start to start, thereby leaving the driver with an impression of inconsistent engine restarting.
The inventors herein have recognized the above-mentioned disadvantages and have developed a method for improving engine starting.
One embodiment of the present description includes a method for starting an engine, comprising: stopping the engine; and during an engine start, adjusting a transmission tie-up force in response to a timing of a first combustion event of a cylinder.
By adjusting a transmission tie-up force in response to an engine event during starting, starting consistency and engine torque management can be improved. For example, transmission clutches can be adjusted based on the timing of a predicted first combustion event of an engine during an engine restart to reduce a torque transfer delay from an engine to a transmission. Further, linking transmission clutch actuation to a more repeatable condition can lessen a driver's perception of inconsistent engine restarting.
The present description may provide several advantages. Specifically, the approach may improve engine starting consistency. In addition, the approach may improve driver demanded wheel torque response time. Further, the approach may simplify a torque management system since torque transfer may be synchronized to an event that is more repeatable and easily identifiable.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.